UNC-CH Physics and Astronomy Colloquium

Matt Bayliss, Massachusetts Institute of Technology

“Gravitational Lensing In the Era of Survey Science”

Since the advent of large-area, high-quality astronomical surveys strong gravitational lensing has transitioned from a small-N to a large-N discipline. Galaxy cluster scale strong lensing, in particular, holds tremendous untapped potential because it lies at the intersection of cosmology, the most massive structures in the Universe, and the magnified distant universe. As a founding member of the Sloan Giant Arcs Survey (SGAS) team, I will summarize our recent progress toward unlocking the scientific potential of large samples of strong lensing systems to address fundamental problems in astrophysics and cosmology. Focusing on recent results that highlight our sophisticated lensing analysis toolbox, I will present several pioneering measurements that we have made using the SGAS sample. These results lay the groundwork for future work that will use large numbers of highly magnified galaxies to answer outstanding questions about the physics of star formation and the properties of the interstellar medium in the epoch during which the Universe formed most of its stars. In addition to their value as natural telescopes, the massive structures that are responsible for the lensing action are, themselves, rare and powerful tools for testing the Lambda-CDM cosmological paradigm via the growth of structure and the mass distributions of lensing clusters. Thinking outside the bounds of vanilla Lambda-CDM, I will discuss how cluster lenses are also excellent laboratories for probing exotic, non-standard cosmologies. Upcoming surveys from LSST and the South Pole Telescope will reveal sample of cluster lenses out to high redshift. With these new systems we will directly observe the first generation of massive galaxy clusters, and the first generation of strong lensing clusters. The leverage from high redshift galaxy cluster samples—including mass calibrations informed by strong lensing studies—will usher in a new and powerful new tool for constraining the nature of Dark Energy and the Cold Dark Matter theory of structure formation.